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  • I had this doubt for a long time , so i am here to post my question and wait for an appropriate answer.Many friends have said that vehicle tyres which have bigger dia will be running a more speed than a cycle which has smaller dia(consider that both wheels run at same rpm).does it require more power to rum a vehicle with bigger wheel or for a vehicle with smaller wheel?Which will cover maximum distance for the given same power ? If the answer is yes that vehicle with high dia goes further, why companies does'nt use bigger wheels for cars,bus,etc.Does it increases overall weight or it increases the overall length and height?
    please clarify my doubt.Also give the appropriate reasons behind the usage of medium sized wheels for vehicles.
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  • Velshankar MJ

    Member • Sep 4, 2013

    The circumference of a circular object, like a wheel, is found by multiplying its diameter by "pi" ("Pi" = 3.1416). This is the same as 2 times the radius multiplied by "pi". As a car rolls down the road, every time its wheels rotate one complete revolution, it travels forward a distance exactly equal to the circumference of its wheels. If bigger diameter wheels are used, circumference increases so the distance it covered also increases. So if the speed of rotation of the car's wheels does not change, the speed of the car is directly proportional to the wheel's radius. Larger radius means higher speed, and smaller radius means slower speed. Of course, you cannot make a car with a top speed of 100 MPH, do 200 MPH, just by putting wheels that are twice as big on it. The motor has to have a lot more power to keep the larger wheels turning the same speed as before, because higher speed requires more power.
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  • Sarathkumar Chandrasekaran

    Member • Sep 4, 2013

    It has passed some light over the question.Thanks Velshankar.I want to know why it was'nt used in race cars if it can give you a lead.I dont think engine does not have power to rotate a bigger dia wheel.I am waiting for more suggestions so that we xan conclude to a overall idea and reason behind the usage.Tagging experts @#-Link-Snipped-# and @wise fool so tgat ee can get a better and exact reason for it.
    There must be a reason for it so thinking again on the topic.
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  • Jeffrey Arulraj

    Member • Sep 5, 2013

    Torque required to start a larger dia wheels from rest to some speed is really high lky

    This torque will not be supplied sufficiently by the engine in the starting strokes itself That makes larger dia for wheels really hard to use

    But some SUV use larger dia as they are not meant for higher speeds. They are mainly meant for larger handling of weight

    SO In my opinion If you want a higher speed car go for a lower dia as torque required will be less. So better pickup

    .But for bulky rides you need larger wheel dia that will boost your performance
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  • Gomathi Shankar

    Member • Sep 5, 2013

    Let me explain this technically. The equation for the torque, as we all know is

    Torque= force x radius

    It means, Force = torque/radius.

    The torque is developed by the engine and available at the road wheels. Force is required to overcome the frictional resistance and move the vehicle from rest or maintain a speed. By increasing the diameter of the wheel, say, if you are using the wheel that is twice the dia, it means the force is halved. Therefore the engine has to produce twice the torque to gain same speed of the vehicle with a smaller wheel. With a same power output from engine, the bigger wheel will run at half speed. If smaller wheel rotates 100 revs, the bigger will be 50 revs. This equals the distance covered by the wheel for a same level of power output.
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